This is not official yet and the motive is still unknown but it seems that it's more like an emotional thing than for the abuse of substances or alcohol.

According to a close source, “She desperately needed help. She seemed to be intoxicated when she checked in because she was acting really erratic. She was extremely emotional, constantly breaking down in tears. She’s not in a good place right now, but thankfully, she’s getting the help she needs.”

I was really surprised of all this coming from her because she's one of the best actresses in her 20s but I guess everyone goes through bad times and needs help. We hope that she gets it and returns to acts as good and professionally as she used to do.